How to check if Double value is negative or not? [closed]

Question

As title suggests, how do i check if particular Double is negative or not. Here is how am getting Double instance

(Double.parseDouble(data[2])

Thoughts, suggestions?

Answer 1

Being pedantic, < 0 won't give you all negative numbers.

double d = -0.0;
System.out.println(d + " compared with 0.0 is " + Double.compare(d, 0.0));
System.out.println(d + " < 0.0 is " + (d < 0.0));

prints

-0.0 compared with 0.0 is -1
-0.0 < 0.0 is false

-0.0 is negative but not less than 0.0

You can use

public static boolean isNegative(double d) {
     return Double.compare(d, 0.0) < 0;
}

A more efficient, if more obtuse, version is to check the signed bit.

public static boolean isNegative(double d) {
     return Double.doubleToRawLongBits(d) < 0;
}

Note: Under IEEE-754 a NaN can have the same signed bit as a negative number.

Answer 2

Double v = (Double.parseDouble(data[2]));
if (v<0){
//do whatever?
}

Answer 3

You could test if it is < 0:

if (Double.parseDouble(data[2]) < 0) {
    // the number is negative
} else {
    // the number is positive
}